DE1078266B - Soap-free lubricating greases based on organopolysiloxanes and phthalocyanines - Google Patents

Description

The common commercially available lubricating greases mostly consist of a mineral oil that is thickened with a metal soap. These fats are up to temperatures of about 120 ° C \ ^r erwendbar, more sophisticated fats this group can also be employed to 140 ° C.

For bearings that have to run at higher temperatures, silicone greases have been used in recent years developed that are resistant up to approx. 190 ° C. These fats consist of a heat-resistant one Phenylmethyl silicone oil thickened with a lithium soap. Since lithium soaps at 190 to 200 ° C melt, it is impossible to use such lubricating greases at working temperatures higher than 190 ° C to be achieved, although the phenylmethyl silicone oil is stable at even higher temperatures were.

Silicone greases, which consist of a silicone oil thickened with a metal soap, also have also have further disadvantages: their lubricity is compared to the commercially available mineral oil lubricating greases much worse; already at a fraction of the Load that a bearing lubricated with mineral oil greases can wear, the lubricating film of such a silicone grease is broken and the bearing begins to Wolf down. It has therefore only been possible to date to cover lightly loaded bearings with silicone grease lubricate. Should such a bearing take on greater loads, the bearing dimensions must can be increased considerably, but this was usually not possible for structural reasons.

In order to meet the requirements for a highly heat-resistant silicone lubricating grease, tried Now you have to replace the metal soap with other heat-resistant, mostly inorganic consistency enhancers. In Various works have been carried out for this purpose silicas, graphite, molybdenum disulphide, mica, clays, reaction products of clays with organic nitrogen bases, various types of soot, dyes, phthalocyanines, Aluminum powder, finely divided gallium, aryl ureas and others. suggested. All of these substances can be although they work together with silicone oils and result in a product of more or less fat-like Consistency, however, all lubricants made with these thickeners have the disadvantage that they have very poor lubricating properties. By excluding any soap, the lubricating effect of the fatty acids is eliminated, and so is the lubrication is almost only caused by the silicone oil content. But since silicone oils are known to have very poor lubricating properties the fats so produced are also poor lubricants. She; show one very high frictional resistance and can only to be used with low bearing loads. - ^

based on organopolysiloxanes

and phthalocyanines

Applicant:

Wacker-Chernie GmbH,
Munich 22, Prinzregentenstr. 22nd

Dr. Siegfried Nitzsche and Dr. Rudolf Riedle,

Burghausen (Obb.),
have been named as inventors

So it is z. B. astonishing that the addition of silicone oils to otherwise good dry lubricants, such as graphite or molybdenum disulfides, whose lubricating effect deteriorates considerably. This can be done with it

explained that the coating of graphite or molybdenum disulphide, which is caused by dry rubbing forms on the lubricating surface, through which the silicone oil is lifted off again. Fortune of it extremely low surface tension, the silicone oil infiltrates such a lubricating film, so that it Can be pushed away and now the silicone oil as a bad lubricant the friction properties of a bearing lubricated in this way.

The possibility of soap-free lubricants based on silicone oil with "one scope of application To produce temperatures above 190 ° C has always had to be done in the past be bought at the cost of a significant deterioration of the overall lubricating properties, since the lubricating effect the fatty acids are omitted from these fats.

In addition, silicone oils containing halogen-containing substituents have also been recommended as lubricants. These oils have compared with the pure silicone oils that halogenfreiekohlenwasserstofrhaltige groups, improved ^/: -Schmiereigenschaften; Their pressure and shear resistance is greater and their coefficient of friction is lower than that of the many unsubstituted silicone oils, but they are still poor in comparison to the mineral oils ¹

... lubricants so that the incorporation of halogen atoms

only a slight improvement in youth "- ^:

If you use these halogen-containing silicone oils

according to = 'the usual- MethMeü' - 'au'S- Metallseifen fats, then compared to the iri "the same way _:

- "made fats from an 'iSilikönöl, which only contains halogen

909 767/375

carries free hydrocarbon residues, no difference in the lubricity to be observed. The lubricating effect of fatty acids is so crucial Influence that the not too significant differences in the lubricity of a halogen-free and a halogen-containing oil do not appear. The lubricating effect of a metal soap grease based on silicone oil is only available from the built-in fatty acids dependent.

Fats or grease-like lubricants made from halogen-containing silicone oils and soap-free thickeners correspond in their lubricating properties to the halogen-containing silicone oils used. How on Already stated above, the silicone oil infiltrates any solid lubricating film that forms, so that this can be pushed aside and the lubricating effect only depends on the properties of the one used Silicone oil is determined. For this reason, no lubricants have yet been used on the basis of halogenated silicone oils used as they do not offer any particular advantages. The problem A satisfactory grease lubrication at temperatures above 190 ° C has not yet been possible be solved.

Surprisingly, it has been found that lubricating greases based on organopolysiloxanes and phthalocyanines have extremely favorable frictional properties if they contain _{, as organopolysiloxanes, those with units of the general formula RSiO 3/2} , in which R is an aromatic hydrocarbon radical substituted by one or more halogen atoms, in particular chlorine atoms .

Only the marked combinations from the multitude of possibilities are not characterized by expected excellent lubricating and other required properties. The new silicone greases have a frictional resistance that is below that of good mineral greases and have a compressive and shear strength that is about three times that is as high as with the previously common and known silicone greases. It was not foreseeable that the Friction resistance of the fats according to the invention is so low, although neither the pure silicone oil nor the pure thickener show such favorable values.

The preferably highly heat-resistant phthalocyanines used according to the invention as thickeners are resistant at the high application temperatures of up to 300 ° C, they do not work with the oil flowing fat-like mass that retains its consistency unchanged even in the heat and does not become one Liquid flows and are completely stable against flexing and shear stresses.

As an example for units of the general formula RSiOgZ ₂ are given:

ClC ₆ H ₄ Si =. Cl ₂ C ₆ H ₃ Si =, Cl ₃ C ₆ H ₂ Si =,
Cl ₄ C ₆ HSi =, Cl ₅ C ₆ Si =, ClC ₆ H ₄ C ₆ H ₄ Si =, ClC ₁₀ H ₆ Si = and BrC ₆ H ₄ Si =.

Other aromatic nuclei can also be carriers for the halogen atoms. On one and the same aromatic nucleus can be different halogen atoms. Likewise is the number of at each core hanging halogen atoms without affecting the application according to the invention.

To heat-resistant silicone oils to obtain any desired viscosity, the halogen-containing groups with known organic silicon groups, the only halogenated hydrocarbon radicals are included, combined by generally known methods. Silicones with the units CH ₃ Si =, (CH ₃ ) ₂ Si =, (CHg) ₈ Si-, C ₆ H ₅ Si =, (C ₈ Hg) ₂ Si =, (C ₆ H ₅ ) (CH ₃ ) Si =, C ₆ H ₅ (CH ₃ ), Si-. C ₂ H ₅ Si =, (C ₂ Hg) ₂ Si =, C ₆ H ₁₁ (CH ₃ ) Si =, and C ₂ H ₃ (CH ₃ ) Si =.

The lubricating greases according to the invention are examined for their lubricating properties in the Almen-Wieland testing machine; In this machine, two steel bearing shells with a strength of about 75 kg / mm ^{2 are placed} against a rotating test shaft

ίο made of steel with a strength of about 85 kg / mm ² hydraulically pressed; The frictional force is measured as the force acting on the circumference of the test wave, which corresponds to the frictional resistance; Furthermore, the pressure is determined at which the lubricating film between the bearing shell and the shaft is squeezed apart and the direct contact of steel on steel results in welding, whereby the test shaft breaks off at its tapered point. If the contact pressure is plotted on the abscissa in a diagram and the frictional force measured on the ordinate, a friction curve is obtained which is the more favorable the flatter it is, ie the lower the frictional resistance at a given pressure load; A good lubricating grease is also indicated by the fact that the curve runs as far to the right as possible, ie that the lubricating film can cope with the gravitational forces at higher pressure loads. The quotient of the frictional force divided by the contact pressure gives the coefficient of friction; this should be the same and as low as possible for every grease in all pressure ranges.

example 1

By means of mixed hydrolysis and subsequent equilibration, one adjusts according to known methods Silicone oil that contains 75 mole percent dimethylsiloxane, 15 mole percent dichlorophenylsiloxane, and 10 mole percent Contains trimethylsiloxane units and has a viscosity of 320 cSt at 25 ° C.

50 g of phthalocyanine are mixed together with this silicone oil, heated at 200 ° C. and raised ground homogeneously on a three-roller mill. The amount of silicone oil used is measured in such a way that that the finished grease has an ASTM penetration of 320 (Grease A).

In the same way, using a commercially available phenylmethyl silicone oil a grease with the same penetration is produced (grease B).

Both greases are made with the Almen-Wieland machine checked. From the values obtained one can see the outstanding properties of the invention

appropriate grease A:

6o Grease A Frictional
koeffi
efficient pressure
durable
speed up
to break
kg Grease B 0.12
0.80 500
200

Example 2

A mixture of 3 kg of dimethyldichlorosilane,

900 g of chlorophenyltrichlorosilane and 750 g of trichlorophenyltrichlorosilane is diluted with 5 l of toluene and

hydrolyzed with an excess of water. The hydrolyzate is then treated with 400 g of hexamethyldisiloxane and 1000 g concentrated sulfuric acid shaken for 24 hours. After neutral washing and distilling off the solvent gives an oil with a viscosity of 730 cSt, measured at 25 ° C. From 50 g of phthalocyanine and the corresponding amount of this halogen-containing silicone oil a grease of penetration 260 is produced on the three-roll mill (grease C).

In the same way, 50 g of microfine molybdenum disulfide for lubricating purposes and this become oil a penetration grease 260 was prepared (grease D).

While the phthalocyanine grease has a non-flowing greasy consistency and maintains this property even when heated to 200 ° C, the lubricating grease D is pasty and not thixotropic and becomes viscous when heated to 200 ° C.

The same oil is also used to make a lithium soap · lubricating grease. 100 g of the halogen-containing silicone oil described and 22 g of stearic acid are melted together. A solution of 3.7 g of LiOH-H ₂ O in 30 g of water is added. The fat stock is then slowly heated up to 150 ° C until all the water has evaporated and the grease obtained in this way is leveled on the three-roller mill

(Fat E). It has a penetration of 270 and remains consistent without flowing when heated up to 190 ° C. Above this temperature the grease turns black with charring and the grease bandage falls off together as the lithium soap melts.

Then the measured values of the three greases and, for comparison, also the values of a commercially available mineral oil grease:

Frictional
koeffi
efficient pressure
durable
speed up
to break
kg Grease C 0.11
0.50
0.10
0.23 550
450
250
650 Grease D Grease E. Mineral oil grease

Example 3

Phthalocyanine and silicone oils of the specified composition are made up by heating 200 ° C and subsequent leveling on the roller mill, the following greases are produced and applied the Almen-Wieland machine tested:

Phthalocyanine + oil of the composition in mole percent Coefficient of friction

Pressure resistance to break

80 (CH ₃ ) ₂ SiO, 12BrC ₆ H ₄ SiO _3/2 , 8 (CH ₃ ) ₃ SiO _1/2

84 (CH ₃ ) ₂ SiO, 10 Br ₃ C ₆ H ₂ SiO ₃ Z ₂ , 6 (CH ₃ ) ₃ SiO _1/2

85 (CH ₃ ) ₂ SiO, 8Cl ₃ C ₆ H ₂ SiO ₃ Z ₂ , 7 (CH ₃ ) ₃ SiO _1/2

70 (CH ₃ ) ₂ Si O, 15 CH ₃ (C ₆ H ₅ ) SiO, 8 Cl ₂ C ₆ H ₃ Si O _3/2 ,

7 (CH ₃ ) ₃ Si0 _1/2 ,

80 (CH ₃ ) ₂ SiO, 15Cl ₂ C ₆ H ₃ (CH ₃ ) SiO, 5 (CH ₃ ) ₃ Si0 _1/2

Commercially available halogen-containing silicone oil

0.10
0.15
0.11

0.12
0.33
0.30

450 600 550

500 400 350

Example 4

The cleaned dry bearings of a ball-bearing electric motor of 1 kW and 1500 rpm are tested with the test greases specified below. The engine is then left at an ambient temperature of 120 ° C, corresponding to a storage temperature of about 150 ° C, respectively Run for 120 hours, check the bearings after cooling down and continue this cycle until the running surfaces of the bearings become rough and begin to seize. This point is usually pretty tough suddenly noticeable from a sharp increase in the running noise. At this point it will Test grease considered to have failed.

Running time in hours

Fat A 1800

Fat B 120

Fat C 1560

Fat D 60

Fat E 100

This test shows even more clearly than the measurement with the Almen-Wieland machine outstanding properties of the silicone greases according to the invention.

Claims (1)

Claim: Soap-free lubricating greases based on organopolysiloxanes and phthalocyanines, characterized in that the organopolysiloxanes contain units of the general formula RSiO _3/2 , in which R is an aromatic hydrocarbon radical substituted by one or more halogen atoms, in particular chlorine atoms. References considered: U.S. Patent No. 2,597,018; Boner: Manufacture and Application of Lubricating Greases (1954), pp. 690 to 697. 909 76T / 375 3. 60